Overlapping UVs Error in Unity when importing from Blender

Question

I’m feeling pretty frustrated right now. I’m trying to import my own assets from Blender into Unity, but I keep getting the error message “There are X objects in the Scene with overlapping UV’s” for every asset. I’ve carefully unwrapped the UV maps and included them in the model. To illustrate my problem, I’ve created a very simple door in Blender:

I marked the sharp edges as seams and unwrapped the UV map. For this simple model, the UV map looks good. When I click on “Select > Select Overlap,” no errors are shown. As mentioned, this is a very basic model meant to highlight the issue I’m facing.

However, when I export it as an FBX and import it into Unity, I get the “Overlapping UVs” error during light baking. In Unity’s UV Overlapping View, the following is displayed:

When I double-check in Blender with the UV grid, I can’t find any overlapping UVs:

So, I’m turning to the community to ask where exactly I might be going wrong or how I can proceed. Any help would be greatly appreciated.

Best regards Jan